"；MySQL消失了”；在PHP守护进程中，使用pcntl_fork

我正在尝试使用PHP守护进程检索数据库值，并为检索到的每个id派生一个实例（使用pcntlfork）。

每个fork都应该做一些工作，然后更改数据库值，这样就不会再检索它了。

然而，例如，当我分叉一个孩子并让它睡眠10秒（实际处理时间）时，MySQL连接似乎超时了。如何防止这种情况发生？try/catch似乎无法阻止该错误。

#!/usr/bin/php
<?php
ini_set('memory_limit','256M');
gc_enable();
function sig_handler($signo) {
  global $child;
  switch ($signo) {
   case SIGCHLD:
     echo "SIGCHLD received'n";
     $child--;
  }
}
// install signal handler for dead kids
pcntl_signal(SIGCHLD, "sig_handler");
global $PIDS; $PIDS = array();
global $maxforks; $maxforks = 5;
global $child; $child = 1;
global $boot; $boot = true;
date_default_timezone_set('Europe/Brussels');
// figure command line arguments
if($argc > 0){
    foreach($argv as $arg){
        $args = explode('=',$arg);
        switch($args[0]){
            case '--log':
                $log = $args[1];
                break;
            case '--msgtype':
                $msgtype = $args[1];
                break;
        } //end switch
    } //end foreach
} //end if
// Daemonizen
$daemon_start = date('j/n/y H:i', time());
$pid = pcntl_fork();
if($pid == -1){
    return 1; // error
} else if($pid) {
    return 0;
} else {    
    while(true){
    try {
        $host = 'localhost';
    $dbname = 'bla';
    $dbuser = 'bla';
    $dbpass = 'bla';
        $db = new PDO('mysql:host='.$host.';dbname='.$dbname.';charset=utf8', $dbuser, $dbpass, array(PDO::ATTR_TIMEOUT => 2));
        //$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
    } catch (PDOException $e){
        echo $e->getMessage();
    }
    $read_messages = $db->query("SELECT * blablabla");
    while($read_message_row = $read_messages->fetch(PDO::FETCH_ASSOC)){
        $id = $read_message_row['id'];
        $pid1 = pcntl_fork();
        if ($pid1 == -1){
                die('could not fork');
        } else { #START ELSE COULD FORK
            $PIDS[$pid1] = $pid1; //KEEP TRACK OF SPAWNED PIDS
            if ($pid1){
                // parent
                if ($child++ >= $maxforks){
                        pcntl_wait($status);
                        $child++;
                }
                echo "Forking child with PID $pid1 voor $id.'n";
                //PARENT THREAD : $ch is a copy that we don't need in this thread
                // child forken
            } else {
                include_once "test_worker.php";
            } // einde child thread
        } //if-else-forked

    }
}
}
?>